| Message ID | 20200123151700.1367857-1-lvivier@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | virtio-rng: add a control queue | expand |
On Thu, Jan 23, 2020 at 04:16:58PM +0100, Laurent Vivier wrote: > The kernel needs sometime to be able to cancel an ongoing command. > > For instance, if the virtio-rng device uses the egd backend > and this backend doesn't provide data, the buffer provided by the > kernel is kept as long as it is needed. > > On the kernel side, a read blocks until the buffer returns from QEMU. > > As the read is done with a mutex held, all the hw_random interface > hangs and we cannot switch to another hw_random backend. > > So this series adds a control queue to the virtio-rng device to allow > to flush the virtio-rng input queue to release the kernel mutex and > to allow to switch to another device. > > The kernel side series can be found at: > > https://github.com/vivier/linux/commits/virtio-rng-ctrl > > Laurent Vivier (2): > virtio-rng: prepare the introduction of a control queue > virtio-rng: add a control queue > > hw/core/machine.c | 1 + > hw/virtio/trace-events | 6 ++ > hw/virtio/virtio-rng.c | 99 ++++++++++++++++++--- > include/hw/virtio/virtio-rng.h | 5 +- > include/standard-headers/linux/virtio_rng.h | 14 +++ > 5 files changed, 111 insertions(+), 14 deletions(-) Where can I find the VIRTIO specification for this new virtqueue? Thanks, Stefan
On Thu, 2020-01-23 at 16:16 +0100, Laurent Vivier wrote: > The kernel needs sometime to be able to cancel an ongoing command. > > For instance, if the virtio-rng device uses the egd backend > and this backend doesn't provide data, the buffer provided by the > kernel is kept as long as it is needed. > > On the kernel side, a read blocks until the buffer returns from QEMU. > > As the read is done with a mutex held, all the hw_random interface > hangs and we cannot switch to another hw_random backend. > > So this series adds a control queue to the virtio-rng device to allow > to flush the virtio-rng input queue to release the kernel mutex and > to allow to switch to another device. > > The kernel side series can be found at: > > https://github.com/vivier/linux/commits/virtio-rng-ctrl Did you submit the kernel series too? Can you please CC me to it? This will need spec changes as well, can you please point me to them too? I also recall a previous discussion about this, but my search-fu is failing to find it... Amit
On 24/01/2020 13:43, Amit Shah wrote: > On Thu, 2020-01-23 at 16:16 +0100, Laurent Vivier wrote: >> The kernel needs sometime to be able to cancel an ongoing command. >> >> For instance, if the virtio-rng device uses the egd backend >> and this backend doesn't provide data, the buffer provided by the >> kernel is kept as long as it is needed. >> >> On the kernel side, a read blocks until the buffer returns from QEMU. >> >> As the read is done with a mutex held, all the hw_random interface >> hangs and we cannot switch to another hw_random backend. >> >> So this series adds a control queue to the virtio-rng device to allow >> to flush the virtio-rng input queue to release the kernel mutex and >> to allow to switch to another device. >> >> The kernel side series can be found at: >> >> https://github.com/vivier/linux/commits/virtio-rng-ctrl > > Did you submit the kernel series too? Can you please CC me to it? No, I didn't. I'd like to have some comments on the QEMU side first. QEMU list is generally more responsive than kernel one. It's why I put the link to my linux branch here. > This will need spec changes as well, can you please point me to them > too? The same here. I didn't update the specs, I'd like to have some comments before. BTW, where can I find the specs to update? Is this https://github.com/oasis-tcs/virtio-spec ? > I also recall a previous discussion about this, but my search-fu is > failing to find it... See [RFC] virtio-rng: add a watchdog https://patchwork.kernel.org/patch/10987983/ Thanks, Laurent
On 24/01/2020 12:02, Stefan Hajnoczi wrote: > On Thu, Jan 23, 2020 at 04:16:58PM +0100, Laurent Vivier wrote: >> The kernel needs sometime to be able to cancel an ongoing command. >> >> For instance, if the virtio-rng device uses the egd backend >> and this backend doesn't provide data, the buffer provided by the >> kernel is kept as long as it is needed. >> >> On the kernel side, a read blocks until the buffer returns from QEMU. >> >> As the read is done with a mutex held, all the hw_random interface >> hangs and we cannot switch to another hw_random backend. >> >> So this series adds a control queue to the virtio-rng device to allow >> to flush the virtio-rng input queue to release the kernel mutex and >> to allow to switch to another device. >> >> The kernel side series can be found at: >> >> https://github.com/vivier/linux/commits/virtio-rng-ctrl >> >> Laurent Vivier (2): >> virtio-rng: prepare the introduction of a control queue >> virtio-rng: add a control queue >> >> hw/core/machine.c | 1 + >> hw/virtio/trace-events | 6 ++ >> hw/virtio/virtio-rng.c | 99 ++++++++++++++++++--- >> include/hw/virtio/virtio-rng.h | 5 +- >> include/standard-headers/linux/virtio_rng.h | 14 +++ >> 5 files changed, 111 insertions(+), 14 deletions(-) > > Where can I find the VIRTIO specification for this new virtqueue? I didn't update the specs. Is https://github.com/oasis-tcs/virtio-spec.git the document to update? Thanks, Laurent
On Fri, Jan 24, 2020 at 03:05:18PM +0100, Laurent Vivier wrote: > On 24/01/2020 12:02, Stefan Hajnoczi wrote: > > On Thu, Jan 23, 2020 at 04:16:58PM +0100, Laurent Vivier wrote: > >> The kernel needs sometime to be able to cancel an ongoing command. > >> > >> For instance, if the virtio-rng device uses the egd backend > >> and this backend doesn't provide data, the buffer provided by the > >> kernel is kept as long as it is needed. > >> > >> On the kernel side, a read blocks until the buffer returns from QEMU. > >> > >> As the read is done with a mutex held, all the hw_random interface > >> hangs and we cannot switch to another hw_random backend. > >> > >> So this series adds a control queue to the virtio-rng device to allow > >> to flush the virtio-rng input queue to release the kernel mutex and > >> to allow to switch to another device. > >> > >> The kernel side series can be found at: > >> > >> https://github.com/vivier/linux/commits/virtio-rng-ctrl > >> > >> Laurent Vivier (2): > >> virtio-rng: prepare the introduction of a control queue > >> virtio-rng: add a control queue > >> > >> hw/core/machine.c | 1 + > >> hw/virtio/trace-events | 6 ++ > >> hw/virtio/virtio-rng.c | 99 ++++++++++++++++++--- > >> include/hw/virtio/virtio-rng.h | 5 +- > >> include/standard-headers/linux/virtio_rng.h | 14 +++ > >> 5 files changed, 111 insertions(+), 14 deletions(-) > > > > Where can I find the VIRTIO specification for this new virtqueue? > > I didn't update the specs. > > Is https://github.com/oasis-tcs/virtio-spec.git the document to update? Yes, please. Stefan
On 29/01/2020 16:43, Stefan Hajnoczi wrote: > On Fri, Jan 24, 2020 at 03:05:18PM +0100, Laurent Vivier wrote: >> On 24/01/2020 12:02, Stefan Hajnoczi wrote: >>> On Thu, Jan 23, 2020 at 04:16:58PM +0100, Laurent Vivier wrote: >>>> The kernel needs sometime to be able to cancel an ongoing command. >>>> >>>> For instance, if the virtio-rng device uses the egd backend >>>> and this backend doesn't provide data, the buffer provided by the >>>> kernel is kept as long as it is needed. >>>> >>>> On the kernel side, a read blocks until the buffer returns from QEMU. >>>> >>>> As the read is done with a mutex held, all the hw_random interface >>>> hangs and we cannot switch to another hw_random backend. >>>> >>>> So this series adds a control queue to the virtio-rng device to allow >>>> to flush the virtio-rng input queue to release the kernel mutex and >>>> to allow to switch to another device. >>>> >>>> The kernel side series can be found at: >>>> >>>> https://github.com/vivier/linux/commits/virtio-rng-ctrl >>>> >>>> Laurent Vivier (2): >>>> virtio-rng: prepare the introduction of a control queue >>>> virtio-rng: add a control queue >>>> >>>> hw/core/machine.c | 1 + >>>> hw/virtio/trace-events | 6 ++ >>>> hw/virtio/virtio-rng.c | 99 ++++++++++++++++++--- >>>> include/hw/virtio/virtio-rng.h | 5 +- >>>> include/standard-headers/linux/virtio_rng.h | 14 +++ >>>> 5 files changed, 111 insertions(+), 14 deletions(-) >>> >>> Where can I find the VIRTIO specification for this new virtqueue? >> >> I didn't update the specs. >> >> Is https://github.com/oasis-tcs/virtio-spec.git the document to update? > > Yes, please. I've updated the specs, Following https://github.com/oasis-tcs/virtio-spec/blob/master/CONTRIBUTING.md, I've opened an issue: https://github.com/oasis-tcs/virtio-spec/issues/83 Is this the good process? Thanks, Laurent
On Tue, Jul 28, 2020 at 03:45:26PM +0200, Laurent Vivier wrote: > On 29/01/2020 16:43, Stefan Hajnoczi wrote: > > On Fri, Jan 24, 2020 at 03:05:18PM +0100, Laurent Vivier wrote: > >> On 24/01/2020 12:02, Stefan Hajnoczi wrote: > >>> On Thu, Jan 23, 2020 at 04:16:58PM +0100, Laurent Vivier wrote: > >>>> The kernel needs sometime to be able to cancel an ongoing command. > >>>> > >>>> For instance, if the virtio-rng device uses the egd backend > >>>> and this backend doesn't provide data, the buffer provided by the > >>>> kernel is kept as long as it is needed. > >>>> > >>>> On the kernel side, a read blocks until the buffer returns from QEMU. > >>>> > >>>> As the read is done with a mutex held, all the hw_random interface > >>>> hangs and we cannot switch to another hw_random backend. > >>>> > >>>> So this series adds a control queue to the virtio-rng device to allow > >>>> to flush the virtio-rng input queue to release the kernel mutex and > >>>> to allow to switch to another device. > >>>> > >>>> The kernel side series can be found at: > >>>> > >>>> https://github.com/vivier/linux/commits/virtio-rng-ctrl > >>>> > >>>> Laurent Vivier (2): > >>>> virtio-rng: prepare the introduction of a control queue > >>>> virtio-rng: add a control queue > >>>> > >>>> hw/core/machine.c | 1 + > >>>> hw/virtio/trace-events | 6 ++ > >>>> hw/virtio/virtio-rng.c | 99 ++++++++++++++++++--- > >>>> include/hw/virtio/virtio-rng.h | 5 +- > >>>> include/standard-headers/linux/virtio_rng.h | 14 +++ > >>>> 5 files changed, 111 insertions(+), 14 deletions(-) > >>> > >>> Where can I find the VIRTIO specification for this new virtqueue? > >> > >> I didn't update the specs. > >> > >> Is https://github.com/oasis-tcs/virtio-spec.git the document to update? > > > > Yes, please. > > I've updated the specs, > > Following > https://github.com/oasis-tcs/virtio-spec/blob/master/CONTRIBUTING.md, > I've opened an issue: > > https://github.com/oasis-tcs/virtio-spec/issues/83 > > Is this the good process? Please post spec changes to the virtio-comment@lists.oasis-open.org mailing list: https://github.com/oasis-tcs/virtio-spec/#providing-feedback Thanks, Stefan
On Tue, Jul 28, 2020 at 03:45:26PM +0200, Laurent Vivier wrote: > On 29/01/2020 16:43, Stefan Hajnoczi wrote: > > On Fri, Jan 24, 2020 at 03:05:18PM +0100, Laurent Vivier wrote: > >> On 24/01/2020 12:02, Stefan Hajnoczi wrote: > >>> On Thu, Jan 23, 2020 at 04:16:58PM +0100, Laurent Vivier wrote: > >>>> The kernel needs sometime to be able to cancel an ongoing command. > >>>> > >>>> For instance, if the virtio-rng device uses the egd backend > >>>> and this backend doesn't provide data, the buffer provided by the > >>>> kernel is kept as long as it is needed. > >>>> > >>>> On the kernel side, a read blocks until the buffer returns from QEMU. > >>>> > >>>> As the read is done with a mutex held, all the hw_random interface > >>>> hangs and we cannot switch to another hw_random backend. > >>>> > >>>> So this series adds a control queue to the virtio-rng device to allow > >>>> to flush the virtio-rng input queue to release the kernel mutex and > >>>> to allow to switch to another device. > >>>> > >>>> The kernel side series can be found at: > >>>> > >>>> https://github.com/vivier/linux/commits/virtio-rng-ctrl > >>>> > >>>> Laurent Vivier (2): > >>>> virtio-rng: prepare the introduction of a control queue > >>>> virtio-rng: add a control queue > >>>> > >>>> hw/core/machine.c | 1 + > >>>> hw/virtio/trace-events | 6 ++ > >>>> hw/virtio/virtio-rng.c | 99 ++++++++++++++++++--- > >>>> include/hw/virtio/virtio-rng.h | 5 +- > >>>> include/standard-headers/linux/virtio_rng.h | 14 +++ > >>>> 5 files changed, 111 insertions(+), 14 deletions(-) > >>> > >>> Where can I find the VIRTIO specification for this new virtqueue? > >> > >> I didn't update the specs. > >> > >> Is https://github.com/oasis-tcs/virtio-spec.git the document to update? > > > > Yes, please. > > I've updated the specs, > > Following > https://github.com/oasis-tcs/virtio-spec/blob/master/CONTRIBUTING.md, > I've opened an issue: > > https://github.com/oasis-tcs/virtio-spec/issues/83 > > Is this the good process? > > Thanks, > Laurent It's ok but you also need to send spec patches by mail so people can review.